<!doctype html> 
<html> 
<head> 
    <meta charset="utf-8"> 
    <title></title> 
</head>
<body>
<script type="text/javascript">
	
function a(){

}
function b(){

}

a.prototype = {
	m:10
}

//console.log(a.__proto__);
//b.prototype = a.prototype;
//b.prototype = new a();
//for in
//Object.setPrototypeOf(b.prototype,a.prototype)
//b.prototype = Object.create(new a())
alert(new b().m);

</script>
</body>
</html>